Fuel pump keeps running

I have a 1990 Ford F150 truck with Fuel Injection. It's got the 5L engine.
For some reason, when the weather is cold, every so often I shut off the ignition switch, and I can hear the electric (in tank) fuel pump
still running. Rotating the key will not stop it. The only thing that works is to restart the truck and shut it off again. This usually stops it. Or I can disconnect a battery cable.
What is causing this, and how do I fix it? The IGN switch shuts everything else off, so I doubt it's the switch itself, unless they have a separate contact just for the fuel pump.
Thanks
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On Mar 11, 2:52 am, snipped-for-privacy@invalid.com wrote:

This is just a wild guess, but it could be the fuel pump relay freezing and sticking. Next time this happens try rapping on the relay with something light and non metalic like a pen or wooden dowel.
Calvin
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On Tue, 11 Mar 2008 07:55:30 -0700 (PDT), Calvin

Thanks Calvin for the advice. However, could you please tell me where this relay is located. I dont have a clue. I'm assuming the relay is direct wired on the output side and the ign switch controls the input or trigger side. I know how relays work, but I dont know it's location. If it's sticking, that sounds like an easy repair, as long as it's in a place thats not hard to reach. I know I need to fix this because it drained my battery once, and I'm sure it's not good for the fuel pump either.
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On Mar 12, 1:26 am, snipped-for-privacy@invalid.com wrote:

Check your owners manual - it should have that info towards the back with the fuses. On my 95 bronco there are two power distro blocks under the hood, but I don't know if that applies to your '90. Usually they are either along the inner fender wall or near the battery. It would be a square plastic shield covering a group of black or grey cubes - the relays themselves.
Calvin
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The same thing happeded once on my old 89 Mustang. The relay latches up because the contacts stick. In my case it was under the drivers seat. You need a new one. Fred
wrote:

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On Wed, 12 Mar 2008 07:04:59 -0700 (PDT), Calvin

Thanks again. I dont have an owners manual. Truck was used, and no manual was included. At least I know what to look for now. I know there is a major power block near the brake master cylinder.
Just curious, this truck had 2 gas tanks and a switch on the dash to select them. I only use the front tank because the rear leaks and the pump is bad in it. Is there a separate relay for each tank?
I may replace that tank when weather allows, but for now, if there are 2 relays, maybe I can just swap them. I suppose they might use the same one for both too ???
I wonder if that Autozone site has any info on this? Guess I'll have to look there.
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